The present invention relates to a backwater valve for use in liquid flow lines to prevent a reversing of the flow stream.
In U.S. Pat. No. 5,406,972 which issued 1995, Gabe Coscarella disclosed a backwater valve with a pivotally mounted closure gate. A float was mounted to the closure gate. The closure gate sat in the liquid stream. As the liquid stream rose the float caused the closure gate to float into a closed position.
The backwater valve described in the Coscarella patent was useful in a variety of applications and has come into widespread commercial usage. There were some applications encountered, however, in which it was not desirable to have the closure gate positioned in the liquid stream.
What is required is an alternative configuration of backwater valve in which the closure gate does not float in the liquid stream.
According to the present invention there is provided a backwater valve which includes a body having a flow passage extending therethrough with an inlet side and an outlet side. A closure gate is pivotally mounted within the body above the inlet side of the flow passage. The closure gate has an open position above the flow passage and a closed position blocking the inlet side of the flow passage. A float activated locking member is mounted on the body. The locking member has a locking position and a release position. In the locking position, the locking member engages and holds the closure gate in the open position. The float activated locking member is influenced by liquid rising in the body whereby the locking member is carried to the release position when the liquid rises above a preset level and upon release the closure gate closes by force of gravity.
With the backwater valve, as described above, the closure gate is held in the open position out of the liquid stream by the locking member. When liquid starts to fill the valve body, the rising liquid carries the locking member to the release position. The locking member then releases the closure gate which falls by force of gravity to the closed position to prevent a reversal of liquid flow back through the inlet side of the flow passage.